1. Field of the Invention
Embodiments of the present invention generally relate to torque load transfer, limitation, and vibration dampening device designs.
2. Description of the Related Art
The increase in power features in vehicles continues to increase power demands from the vehicle's electrical system. As a result, charging and starting units and hybrid motor designs have incrementally increased amperage output to over 200 amps.
The larger starters and alternators combined with more complex engine accessories now found in the serpentine belt system, lead to rotational torque load spikes. These spikes are transferred to the alternator via its pulley. If either not dampened or too high, they can potentially damage the charging unit or other components in the belt system, including the belt itself.
To mitigate some of these problems, vibration dampening pulley designs have been conceived and implemented in charging units. Likewise, larger roll clutch or specially heat treated roll clutch drives have been attempted to carry the larger torque loads. A prominent pulley design relies on the use of a roll clutch mechanism to overrun and absorb loads. Another prominent pulley design relies on the use a combination coil spring and phenolic friction clutch mechanism to overrun and absorb loads.
However, neither of these designs have proven sufficiently durable for the noted applications. The roll clutch design requires high quality heat treated alloy steel components, tends to overheat and fail after extended overrun conditions, and slips under permanent mechanical deformation when faced with frequent, high torque loads.
The spring and friction clutch mechanism is complex in design, tends to early spring fatigue failures, builds up heat and cracks the clutch mechanism, and is nearly impossible to ascertain its remaining end of life balance without scrupulous technical inspection of the spring metallography and phenolic material conditions.
Thus, a need exists for a simple design that may offer one or more of greater durability, lower heat generation, capability of carrying high torque loads, potentially tunable vibration dampening, tunable to maximum permissible torque loads before elastic (repeatable) slippage, and/or ease of end of life assessment.